I only scan it when I do something with it.

Other than that there's no point.

Here is the answer to your problems Soriku....just get a Mac!

@topic,

My AV scans once a day early in the morning when I had assumed I would be asleep but am frequently not =P 

 *snicker*

 *snort*

 Whatever you say, man. Whatever you say.

My computer runs a virus scan every 3 hours its inactive. I have Norton, it comes free with my internet.

For my windows machine, it comes on at 4 or 5 am or something and run automatically. For those near the start saying about defrag, with XP, I check about every month or so for the first year I had it since Iwas used to having to do it in 98, but it was always a low enough fragmentation level that doing it wouldn't really help. *shrug*
My linux laptop has only been up and running for a few weeks, but I'm not too concerned about it.

Mac OSX sets new files to executable. Linux sets new files to not be executable. A virus is something that is executed without user intervention. Mac and Linux are both susceptible to Malware, Trojan Horses, Program Vulnerabilities and so on.

Why you would not use a Scanner on a Mac or Linux is beyond me. You can still fall victim to say a keylogger in Firefox or a Vulnerability in Apache that can allow access to your system.

Indeed. However, Linux is more secure by design due to their being a vastly wider pool of developers that can fix vulnerabilities and well-documented, open code that facilitates them doing so.

Social engineering attacks are inherent to every OS, but not having root access by default as Linux users do limits the damage to the user's directory only, which only contains documents: no programs, no sensitive data nd no system files. The home directory is backed up frequently too, so you might lose a day's work at worst. Programs like keyloggers don't work when website scripting is disabled.

Mac OS X is only secure to the extent that it is based on BSD, which itself is based on the same principles and often the same code as a Linux system. Every addition Apple makes to it makes it less secure and less stable, because they use the same principles as Windows of having closed development, letting the developers fall into bad coding practices and assuming the user is a computer expert who knows how to protect their computer.

Never. I use Windows, GNU/Linux and O/S X.

Never I use mac osx :)

I never run full system scans. It's like shutting the stable door after the horse has bolted. As long as your AV is up to date then you should be fine.
In my experience, the first thing virii do when they infect your pc is shutdown/disable your AV. If you are protected then the virii will not get in in the first place. Unless its Chuck Norris.